1. Field of the Invention
The present invention concerns a method and an apparatus for planning and implementing selective internal radiation therapy (SIRT).
2. Description of the Prior Art
Interventional oncology provides an increasing number of minimally invasive treatment options, among them being a procedure called selective internal radiation therapy (SIRT).
SIRT is a non-surgical outpatient therapy that makes use of radioactive microspheres, called SIR-Spheres®, to deliver radiation directly to the site of one or more liver tumors. This targeted therapy preserves healthy tissue while delivering up to forty more times radiation to the liver tumors than would be possible using conventional radio-therapy.
It is very important for treating liver cancer to bring as much of the therapeutic agent (e.g. SIR-Spheres® in the case of SIRT) as possible to the tumor itself. It is also important, however, to prevent the surrounding tissues from being damaged by the destructive impact of the therapeutic agent. It is therefore very beneficial for the treating physician to have knowledge, which is as precise as possible, regarding the location of the tumor, and the location and anatomy of the tumor-feeding vessels (called “feeders”). In other words, it is extremely important to know the blood volume feeding the tumor.
In order to calculate the overall dose of the therapeutic agent (and to make a requisition for this amount of the therapeutic agent) the physician must also know information about the patient's height and weight, in order to calculate the body surface area (BSA), the volume of the entire volume (i.e. the complete organ), and the volume of each tumor to be treated. The determination of all of the above parameters is critical, because the more precise the dose delivery via the different feeders can be made, the better the outcome (i.e., therapy success).
Among the aforementioned factors, it would also be useful to know which of multiple feeding vessels supply which tumors, among multiple tumors, and how much liver volume is effected (fed) by each feeding vessel. The more exact the dose delivery can be made via the different tumor vessels, by advance calculation, the better effect the delivery of the therapeutic agent will have in treating the tumor or tumors. If the overall dose of the radioactive microspheres is split among the different feeding vessels according to their respective percentages with regard to feeding the tumor or tumors, the more effective the treatment can be made.
The conventional workflow for SIRT is as follows.
A pre-procedural computed-tomography (CT) imaging is implemented to visualize the tumor and its feeding vessels. A volume measurement is made using the pre-procedural CT dataset at a workstation, in order to identify the volume of the tumor and to then roughly estimate the amount of radioactive material that is required for the desired treatment. Although a quantitative blood volume measurement is available through the CT dataset, only the overall amount of radioactive material can be calculated because the blood volume measurement is performed with an intravenous injection. This means that the physician does not know how much of the overall dose needs to be introduced into the individual, respective feeding vessels.
A catheter intervention is then implemented in the angio-suite, in order to embolize the feeding vessels of the tumor with the radioactive microspheres. The patient is then transferred to the CT suite in order to control the embolization. A second catheter invention is made in the angio-suite, if the embolization result was not adequate. A final check of the overall procedural result is then made in the CT suite.